1. Field of the Invention
The present invention generally involves the field of technology pertaining to animated toys and ornaments. More specifically, the invention relates to an improved mechanism for imparting an oscillating movement to a toy or ornament from the output of a power drive source, such as a music box mechanism.
2. Description of the Prior Art
It is known to impart oscillating movements to ornamental objects, such as dolls, supported on a housing by a windup or electric music producing mechanism. This is conventionally realized by providing the power output shaft of the mechanism with a rotating cam assembly having a cam element. A tappet rod supporting the object is rotatably journalled through a wall of the housing and secured to a cam follower arm. The cam element is slidably disposed within a slot provided in the follower arm so that rotation of the cam assembly by the output shaft imparts an oscillating movement to the tappet rod about its longitudinal axis and thereby cause a corresponding oscillation of the object supported thereon.
A conventional oscillating mechanism of this type is based on the concept of a sliding block disposed within a sliding groove, and is also known as a rocker arm reciprocating mechanism. The concept is known in the machine tool industry and is utilized in a shaper machine for cutting a rapidly reciprocating workpiece.
Such a mechanism is inherently incapable of providing a uniform and balanced oscillating-movement to an ornamental object. This is because the geometric relationship between the cam follower arm and its associated cam assembly describes two arcuate paths travelled by the cam element, the beginning and end of the paths being defined by radii extending outwardly from the cam assembly axis of rotation and intersecting the cam element at two points establishing the extreme limits of the oscillation. Since the cam element must travel along a longer arcuate path during the forward half of the oscillation than the arcuate path required for completing the return half of the movement, it is therefore apparent that each half of the oscillation is completed over a different time interval and speed. This results in a nonuniform oscillation of the object.